can we prove the formula to find the area of an octagon

Answer 1

if answer is yes, then how can we prove the formula.

Answer 2

of course the answer is yes, assuming the formula is correct.

Now the question is, what is the formula?

Answer 3

1/2((x/sinT)squared)*sinL*N
T is 360 divided by n
L is (180-T) over 2
N is no of sides

Just came up with this , still only checking it though